1. Technical Field
The present disclosure relates generally to microwave antennas. More particularly, the present disclosure is directed to radiation detectors for microwave ablation antennas.
2. Background of Related Art
Treatment of certain diseases requires destruction of malignant tissue growths (e.g., tumors). It is known that tumor cells denature at elevated temperatures that are slightly lower than temperatures injurious to surrounding healthy cells. Therefore, known treatment methods, such as hyperthermia therapy, heat tumor cells to temperatures above 41° C., while maintaining adjacent healthy cells at lower temperatures to avoid irreversible cell damage. Such methods involve applying electromagnetic radiation to heat tissue and include ablation and coagulation of tissue. In particular, microwave energy is used to coagulate and/or ablate tissue to denature or kill the cancerous cells.
Microwave energy is applied via microwave ablation antennas that penetrate tissue to reach tumors. There are several types of microwave antennas, such as monopole and dipole, in which microwave energy radiates perpendicularly from the axis of the conductor. A monopole antenna includes a single, elongated microwave conductor whereas a dipole antenna includes two conductors. In a dipole antenna, the conductors may be in a coaxial configuration including an inner conductor and an outer conductor separated by a dielectric portion. More specifically, dipole microwave antennas may have a long, thin inner conductor that extends along a longitudinal axis of the antenna and is surrounded by an outer conductor. In certain variations, a portion or portions of the outer conductor may be selectively removed to provide more effective outward radiation of energy. This type of microwave antenna construction is typically referred to as a “leaky waveguide” or “leaky coaxial” antenna.
During microwave ablation, unintended field exposure to healthy tissue may occur due to incorrect device use. For example, damage to healthy tissue may occur if a surgeon inserts the probe to an insufficient depth while performing an ablation, the probe slipping out due to surgeon error or fatigue, or activation of the probe prior to placing the probe in tissue. Also, the repercussions of the unintended field exposure may increase during laparoscopic procedures due to high field intensities as a result of an insufflated abdomen acting as a resonant microwave cavity. Burns to the abdominal wall along device/probe insertion tracks have occurred due to these factors.